阅读说明：本技术 一种交联低烟无卤阻燃聚烯烃电缆料及其制备方法 (Cross-linked low-smoke halogen-free flame-retardant polyolefin cable material and preparation method thereof ) 是由 董建东 何亚丽 于 2020-07-23 设计创作，主要内容包括：本申请公开了一种交联低烟无卤阻燃聚烯烃电缆料及其制备方法,涉及电缆料技术领域。其技术要点是：其原料包括如下重量份数的组分：基材80-110份；构皮纤维20-30份；偶联剂2-6份；无机阻燃剂60-80份；抗氧剂0.1-0.3份；光稳定剂0.3-0.5份；润滑剂0.5-1份；交联剂1.5-3份；所述基材包括如下重量份数的组分：线型低密度聚乙烯树脂25-40份；高密度聚乙烯25-30份；聚1-丁烯30-40份。本申请具有在保证较好阻燃性的同时,提高了电缆料的抗开裂性能的优点。(The application discloses a cross-linked low-smoke halogen-free flame-retardant polyolefin cable material and a preparation method thereof, and relates to the technical field of cable materials. The technical key points are as follows: the raw materials comprise the following components in parts by weight: 80-110 parts of a base material; 20-30 parts of paper mulberry fiber; 2-6 parts of a coupling agent; 60-80 parts of an inorganic flame retardant; 0.1-0.3 part of antioxidant; 0.3-0.5 part of light stabilizer; 0.5-1 part of lubricant; 1.5-3 parts of a cross-linking agent; the base material comprises the following components in parts by weight: 25-40 parts of linear low-density polyethylene resin; 25-30 parts of high-density polyethylene; 30-40 parts of poly-1-butene. The cable material has the advantage of improving the cracking resistance of the cable material while ensuring better flame retardance.)

1. The cross-linked low-smoke halogen-free flame-retardant polyolefin cable material is characterized by comprising the following components in parts by weight:

80-110 parts of a base material;

20-30 parts of paper mulberry fiber;

2-6 parts of a coupling agent;

60-80 parts of an inorganic flame retardant;

0.1-0.3 part of antioxidant;

0.3-0.5 part of light stabilizer;

0.5-1 part of lubricant;

1.5-3 parts of a cross-linking agent;

the base material comprises the following components in parts by weight:

25-40 parts of linear low-density polyethylene resin;

25-30 parts of high-density polyethylene;

30-40 parts of poly-1-butene.

2. The cross-linked low-smoke halogen-free flame-retardant polyolefin cable material as claimed in claim 1, wherein the preparation method of the sheath forming fiber comprises the following steps:

step one, taking 40-50 parts of paper mulberry bark, drying, cutting into blocks, crushing, performing ball milling treatment, and screening to obtain crude fibers;

step two, adding 2-3 parts of sodium hydroxide into 100-150 parts of water, uniformly mixing to obtain a mixed solution, adding the crude fiber into the mixed solution, boiling for 10-15min, naturally cooling to 70-80 ℃, adding 3-6 parts of hydrogen peroxide and 0.1-0.3 part of sodium lignosulfonate, continuously keeping the temperature at 70-80 ℃, heating for 5-10min, filtering, washing with tap water, and drying to obtain the paper-mulberry fiber.

3. The cross-linked low-smoke halogen-free flame-retardant polyolefin cable material as claimed in claim 2, wherein the preparation method of the sheath forming fiber comprises the following steps:

step one, drying paper mulberry bark, cutting the paper mulberry bark into blocks, crushing the blocks, performing ball milling treatment, and screening the crushed blocks to obtain crude fibers;

step two, adding 2-3 parts of sodium hydroxide into 100-150 parts of water, uniformly mixing to obtain a mixed solution, adding the crude fiber into the mixed solution, boiling for 10-15min, naturally cooling to 70-80 ℃, adding 3-6 parts of hydrogen peroxide and 0.1-0.3 part of sodium lignosulfonate, continuously keeping the temperature at 70-80 ℃, heating for 5-10min, filtering, washing with tap water, and drying to obtain alkali-treated fiber;

adding 7-9 parts of dried lithium chloride into 90-100 parts of dimethylacetamide, heating to 75-80 ℃ for dissolving, and cooling to room temperature to obtain a dissolved solution;

and step four, adding the alkali-treated fiber, 2-4 parts of caprolactam and 0.5-1 part of ammonium ceric nitrate into the dissolving solution, mixing and stirring uniformly, reacting for 10-20min, and precipitating, washing, filtering and drying to obtain the fiber with the bark.

4. The cross-linked low-smoke halogen-free flame-retardant polyolefin cable material as claimed in claim 1, wherein the inorganic flame retardant comprises one or more of magnesium hydroxide, aluminum hydroxide and crystal form II ammonium polyphosphate.

5. The cross-linked low-smoke halogen-free flame-retardant polyolefin cable material as claimed in claim 4, wherein the inorganic flame retardant comprises 30-35 parts of magnesium hydroxide, 25-35 parts of aluminum hydroxide and 5-10 parts of crystal form II ammonium polyphosphate.

6. A cross-linked low smoke zero halogen flame retardant polyolefin cable material as claimed in claim 1, wherein said cross-linking agent is composed of 0.3-0.6 parts of 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide, 0.4-0.8 parts of dicumyl peroxide, 0.5-1.0 parts of vinyltriethoxysilane, 0.3-0.6 parts of diethylenetriamine.

7. The cross-linked low-smoke halogen-free flame-retardant polyolefin cable material as claimed in claim 1, wherein the antioxidant is any one of 2, 6-tertiary butyl-4-methylphenol, bis (3, 5-tertiary butyl-4-hydroxyphenyl) sulfide, and pentaerythrityl tetrakis [ beta- (3, 5-tertiary butyl-4-hydroxyphenyl) propionate ].

8. The preparation method of the cross-linked low-smoke halogen-free flame-retardant polyolefin cable material as claimed in any one of claims 1 to 7, comprising the steps of:

step one, heating high-density polyethylene to a molten state, adding linear low-density polyethylene resin, poly-1-butylene, a cross-linking agent and paper-making fibers, uniformly mixing, and banburying for 2-3min to obtain a product one;

step two, sequentially adding an inorganic flame retardant and a coupling agent into the product I, and banburying for 2-4min to obtain a product II;

and step three, adding an antioxidant, a light stabilizer and a lubricant into the product II, banburying for 5-8min, and then extruding, cooling, granulating and screening to obtain the cross-linked low-smoke halogen-free flame-retardant polyolefin cable material.

Technical Field

The application relates to the technical field of cable materials, in particular to a cross-linked low-smoke halogen-free flame-retardant polyolefin cable material and a preparation method thereof.

Background

The plastic used for the insulation and the sheath of the electric wire and the electric cable is commonly called as a cable material, and comprises various varieties such as rubber, plastic, nylon and the like. Polyolefin materials are main forage materials for preparing cable materials, belong to flammable materials, when an external fire source or internal faults exist in the operation process of wires and cables, the wires and cables are easy to burn, in order to reduce fire loss, a flame retardant is required to be added into the materials to realize flame retardance of the wires and cables, the additive flame retardant is added into polymers through a mechanical mixing method to enable the polymers to have flame retardance, and common flame retardants mainly comprise inorganic metal hydroxides and halogen-containing flame retardants. Inorganic metal hydroxide is decomposed in the combustion process to absorb a large amount of heat, and simultaneously, the generated oxide can coat the surface of the polymer so as to isolate air and heat and achieve the flame retardant effect; halogen-containing flame retardants generate hydrogen halide in the heating and burning process, dilute surrounding air, capture hydroxyl radicals and inhibit flame, and halogen-containing flame retardants have high-efficiency flame-retardant characteristics and have little influence on the performance of base materials, but the flame retardants can release gases harmful to human bodies in the burning process and pollute the environment, and are gradually replaced by halogen-free flame retardants.

The invention discloses a halogen-free flame-retardant cable material in Chinese patent with publication number CN104017261B, which comprises the following raw materials in parts by weight: 60-80 parts of LDPE resin, 15-25 parts of EPDM resin, 5-15 parts of EVA resin, 70-90 parts of aluminum hydroxide and 6-8 parts of red phosphorus.

With respect to the related art among the above, the inventors consider that the following drawbacks exist: although the addition of the inorganic flame retardant aluminum hydroxide can achieve a good flame-retardant improvement effect, the inorganic flame retardant aluminum hydroxide in the formula has to have a large filling amount to enable the cable material to have good flame retardance, the compatibility of the inorganic flame retardant and organic matters is poor, and the excessive addition of the aluminum hydroxide can cause the cable material to crack easily and influence the physical and mechanical properties of the material.

Disclosure of Invention

Aiming at the defects in the prior art, the first purpose of the invention is to provide a cross-linked low-smoke halogen-free flame-retardant polyolefin cable material, which improves the cracking resistance of the cable material while ensuring better flame retardance.

The second purpose of the invention is to provide a preparation method of the cross-linked low-smoke halogen-free flame-retardant polyolefin cable material, and the cable material prepared by the method ensures better flame retardance and improves the cracking resistance of the cable material.

In order to achieve the first object, the invention provides the following technical scheme:

the cross-linked low-smoke halogen-free flame-retardant polyolefin cable material comprises the following raw materials in parts by weight:

80-110 parts of a base material;

20-30 parts of paper mulberry fiber;

2-6 parts of a coupling agent;

60-80 parts of an inorganic flame retardant;

0.1-0.3 part of antioxidant;

0.3-0.5 part of light stabilizer;

0.5-1 part of lubricant;

1.5-3 parts of a cross-linking agent;

the base material comprises the following components in parts by weight:

25-40 parts of linear low-density polyethylene resin;

25-30 parts of high-density polyethylene;

30-40 parts of poly-1-butene.

By adopting the technical scheme, the low-density polyethylene resin has higher softening temperature and melting temperature, high strength, good toughness, high rigidity, good heat resistance and cold resistance, and good environmental stress crack resistance, impact strength, tear strength and other properties; the high-density polyethylene has good heat resistance and cold resistance, good chemical stability, higher rigidity and toughness, good mechanical strength, and better hardness, tensile strength and creep property than the low-density polyethylene; the wear resistance and the electrical insulation are good; the chemical resistance, aging resistance and electrical insulation of the poly-1-butene are similar to those of polypropylene. But after being cooled and crystallized from a melt state, the crystal can be changed into a stable crystal form at room temperature, the strength and the rigidity are improved, and the creep resistance, the environmental stress cracking resistance and the impact resistance of the crystal are very excellent and are superior to those of polyethylene; therefore, the linear low-density polyethylene resin, the high-density polyethylene and the poly-1-butylene are compounded for use, so that the strength, toughness, heat resistance, cold resistance, tensile strength and creep property of the base material are improved, and the environmental stress cracking resistance and the impact resistance are improved.

The flame retardant comprises an inorganic flame retardant and an organic flame retardant, wherein the inorganic flame retardant has good thermal stability, is non-volatile and has a lasting effect, is fully mixed with a high polymer in a physical dispersion state, plays a flame retardant role through chemical or physical change in a gas phase or condensed phase, and has better flame retardant, synergistic flame retardant and smoke suppression functions when added into a base material. The paper-making fiber is a plant bast fiber, has extremely high toughness, extremely good water absorption and moisture absorption, air permeability and high elasticity, and the mechanical properties of the base material, including higher tensile strength, impact strength, toughness, good creep resistance and aging resistance, are improved by adding the paper-making fiber into the base material; one part of the coupling agent is an inorganic group which can act with the inorganic filler, the other part is an organic group which can act with the resin or the paper-making fiber, an interface layer is formed between the inorganic filler and the resin substrate or the paper-making fiber, and the interface layer can transfer stress, so that the bonding strength between the inorganic filler and the resin is enhanced, the cracking resistance of the composite material is improved, other media can be prevented from permeating into the interface, the interface state is improved, and the aging resistance and the stress resistance are improved.

The oxidation of the polyolefin is an aging process of autocatalytic chain reaction, namely once oxidation occurs, the speed of the oxidation is faster and faster, and the oxidation reaction of the polyolefin can be inhibited or prolonged by adopting the antioxidant so as to achieve the purpose of preventing the oxidation of the polymer, thereby improving the oxidation resistance of the cable material, delaying the aging of the cable material and prolonging the service life of the cable material.

The light stabilizer is adopted, which can shield or absorb the energy of ultraviolet rays, quench singlet oxygen, decompose hydroperoxide into inactive substances and the like, so that the possibility of photochemical reaction can be eliminated or slowed down and the photo-aging process can be prevented or delayed under the radiation of light to the high molecular polymer, thereby achieving the purpose of prolonging the service life of the cable material. The lubricant has good compatibility with the polymer, and plays a role in reducing the cohesion among polymer molecules in the polymer, thereby improving the internal friction heat generation of the cable material melt and the fluidity of the melt. By adopting the cross-linking agent, the tensile strength, the impact strength, the heat resistance and the chemical resistance of the polyolefin are improved after cross-linking, and meanwhile, the creep resistance, the wear resistance, the environmental stress resistance, the cracking resistance and the bonding property of the polyolefin are also improved.

Further preferably, the preparation method of the paper-mulberry fiber comprises the following steps:

step one, taking 40-50 parts of paper mulberry bark, drying, cutting into blocks, crushing, performing ball milling treatment, and screening to obtain crude fibers;

step two, adding 2-3 parts of sodium hydroxide into 100-150 parts of water, uniformly mixing to obtain a mixed solution, adding the crude fiber into the mixed solution, boiling for 10-15min, naturally cooling to 70-80 ℃, adding 3-6 parts of hydrogen peroxide and 0.1-0.3 part of sodium lignosulfonate, continuously keeping the temperature at 70-80 ℃, heating for 5-10min, filtering, washing with tap water, and drying to obtain the paper-mulberry fiber.

By adopting the technical scheme, the fibers in the paper mulberry bark are extracted, firstly, the paper mulberry bark powder is subjected to ball milling treatment, so that inherent cracks on the surface of the powder are expanded under the action of grinding pressure stress repeatedly, and then the powder is subjected to plastic deformation, and the paper mulberry bark fibers are boiled in a sodium hydroxide solution, so that the paper mulberry bark fibers are conveniently prepared by chemical degumming, and the colloid can be removed as much as possible on the premise of not damaging or damaging the cellulose as little as possible; after the added sodium lignosulfonate is oxidized and modified by hydrogen peroxide, the sodium lignosulfonate and fibers form ideal chemical bond combination in the heating process, the crystal structure of the fibers is unchanged, and the prepared sheath fiber is added into the cable material, so that the impact resistance and the crack resistance of the cable material are improved.

Further preferably, the preparation method of the paper-mulberry fiber comprises the following steps:

step one, drying paper mulberry bark, cutting the paper mulberry bark into blocks, crushing the blocks, performing ball milling treatment, and screening the crushed blocks to obtain crude fibers;

step two, adding 2-3 parts of sodium hydroxide into 100-150 parts of water, uniformly mixing to obtain a mixed solution, adding the crude fiber into the mixed solution, boiling for 10-15min, naturally cooling to 70-80 ℃, adding 3-6 parts of hydrogen peroxide and 0.1-0.3 part of sodium lignosulfonate, continuously keeping the temperature at 70-80 ℃, heating for 5-10min, filtering, washing with tap water, and drying to obtain alkali-treated fiber; adding 7-9 parts of dried lithium chloride into 90-100 parts of dimethylacetamide, heating to 75-80 ℃ for dissolving, and cooling to room temperature to obtain a dissolved solution;

and step four, adding the alkali-treated fiber, 2-4 parts of caprolactam and 0.5-1 part of ammonium ceric nitrate into the dissolving solution, mixing and stirring uniformly, reacting for 10-20min, and precipitating, washing, filtering and drying to obtain the fiber with the bark.

By adopting the technical scheme, the fibers in the paper mulberry bark are extracted, the paper mulberry bark fibers are prepared by chemical degumming, then the paper mulberry bark fibers are added into a dimethylacetamide solution of lithium chloride, ammonium ceric nitrate is used as an initiator, so that the paper mulberry bark fibers and caprolactam generate graft copolymerization reaction, and the caprolactam is grafted on cellulose macromolecules based on free radical initiation; the fiber has stronger rigidity, high crystallinity and excellent mechanical and mechanical properties; caprolactam has the advantages of high fracture strength and fatigue strength and good impact resistance; therefore, the problems of poor thermoplasticity and difficult processing of the fiber material can be solved, the blending compatibility of the fiber and the synthetic resin is improved, and the crack resistance of the cable material is improved.

More preferably, the inorganic flame retardant comprises one or more of magnesium hydroxide, aluminum hydroxide and crystal II type ammonium polyphosphate.

By adopting the technical scheme, the magnesium hydroxide has good flame retardant effect, can reduce the smoke amount during combustion, plays a role of a smoke suppressant, and has the advantages of good thermal stability during high-temperature processing and the like; the aluminum hydroxide has the advantages of good stability, no generation of toxic gas at high temperature, reduction of smoke generation amount during plastic combustion and the like, and has lower dehydration heat absorption temperature and obvious flame retardant effect at the beginning of combustion; the crystal II type ammonium polyphosphate is a halogen-free environment-friendly flame retardant with a nitrogen-containing structure, and has high polymerization degree, good thermal stability and small hygroscopicity. The expanded carbon layer of the product achieves the flame-retardant effects of heat insulation and air isolation in the combustion process, and has low smoke, low toxicity and no molten drops. The cable material has low precipitation rate and good weather resistance and electrical property in a cable material system, thereby improving the weather resistance of the cable material and further improving the anti-cracking property of the cable material. The smoke generation amount is extremely low during combustion, the flame retardance is good, and hydrogen halide is not generated in the flame retardant process. The smoke-eliminating agent is mixed with other flame retardants, has better dispersibility, eliminates smoke and is safe to use.

More preferably, the inorganic flame retardant comprises 30-35 parts of magnesium hydroxide, 25-35 parts of aluminum hydroxide and 5-10 parts of crystal II type ammonium polyphosphate.

By adopting the technical scheme, the decomposition temperature of the magnesium hydroxide is higher, and the heat absorption capacity is smaller at about 340-490 ℃, so that the performance of inhibiting the temperature rise of the material is poorer than that of aluminum hydroxide, and the carbonization flame-retardant effect on the polymer is better than that of the aluminum hydroxide. Therefore, the two are used in a composite way and are complementary to each other, and the flame retardant effect is better than that of single use; when the crystal II type ammonium polyphosphate, the magnesium hydroxide and the aluminum hydroxide flame retardant are used simultaneously, a synergistic effect can be generated to play a good flame retardant effect, the dispersity is good, and the smoke abatement effect is achieved; however, because the production cost of the crystal II type ammonium polyphosphate is high, and the product price is also high, the crystal II type ammonium polyphosphate is added in 5-10 parts for compounding with the magnesium hydroxide and the aluminum hydroxide, so that the flame retardance, the dispersibility and the like of the crystal II type ammonium polyphosphate are improved, and the production cost is effectively reduced.

More preferably, the crosslinking agent is composed of 0.2 to 0.4 part of 2, 5-dimethyl-2, 5-di-tert-butylperoxyhexane, 0.4 to 0.8 part of dicumyl peroxide, 0.6 to 1.2 parts of vinyltriethoxysilane, and 0.3 to 0.6 part of diethylenetriamine.

By adopting the technical scheme, the 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide is a high-temperature cross-linking agent, can improve the strength, the hardness and the like of a product when used in polyolefin, but can cause the too high hardness of a cable material to cause easy cracking when the content of the cable material is large; dicumyl peroxide is used as a cross-linking agent, so that the aging resistance, the insulativity and the processability of the polyolefin product can be improved, and the heat resistance is improved; the vinyl triethoxysilane serving as a cross-linking agent can improve the mechanical property of the material, so that the anti-cracking property of the cable material is improved; diethylenetriamine can be used as a cross-linking agent to improve the stability of the material, and can be used as a curing agent in resin; therefore, the crosslinking agent is compounded by the 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide, dicumyl peroxide, vinyl triethoxysilane and diethylenetriamine in the proportion, and the aging resistance, the mechanical property, the crack resistance and the like of the cable material are improved.

More preferably, the antioxidant is any one of 2, 6-tertiary butyl-4-methylphenol, bis (3, 5-tertiary butyl-4-hydroxyphenyl) sulfide, and pentaerythrityl tetrakis [ beta- (3, 5-tertiary butyl-4-hydroxyphenyl) propionate.

By adopting the technical scheme, 2, 6-tertiary butyl-4-methylphenol, bis (3, 5-tertiary butyl-4-hydroxyphenyl) thioether and tetra [ beta- (3, 5-tertiary butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester are hindered phenol antioxidants and are phenol compounds with space obstruction, the heat oxidation resistance effect of the hindered phenol antioxidants is remarkable, products cannot be polluted, the oxidation resistance of cable materials can be effectively improved, the oxidation of the cable materials is slowed down or inhibited, and the cable materials are prevented from being easily cracked due to oxidation to influence the performance.

In order to achieve the second object, the invention provides the following technical scheme:

a preparation method of a cross-linked low-smoke halogen-free flame-retardant polyolefin cable material comprises the following steps:

step one, heating high-density polyethylene to a molten state, adding linear low-density polyethylene resin, poly-1-butylene, a cross-linking agent and paper-making fibers, uniformly mixing, and banburying for 2-3min to obtain a product I;

step two, sequentially adding an inorganic flame retardant and a coupling agent into the product I, and banburying for 2-4min to obtain a product II;

and step three, adding an antioxidant, a light stabilizer and a lubricant into the product II, banburying for 5-8min, and then extruding, cooling, granulating and screening to obtain the cross-linked low-smoke halogen-free flame-retardant polyolefin cable material.

By adopting the technical scheme, high-density polyethylene, linear low-density polyethylene resin, poly-1-butylene, a cross-linking agent and a skin-forming fiber are firstly mixed to generate a cross-linking reaction, so that polymer chains are connected into a three-dimensional space net-shaped macromolecule through branch chains to form a cross-linked structure, and various physical properties after cross-linking are greatly changed, wherein the most obvious properties influenced by the cross-linking density are modulus, hardness and anti-cracking property; the carbon-carbon crosslinking bond with higher bond energy is beneficial to improving the thermal-oxidative aging resistance. Adding an inorganic flame retardant and a coupling agent in the second step to enable the inorganic-philic group of the coupling agent to act with the inorganic filler or the reinforcing material; and the other part of the organophilic groups react with the synthetic resin, so that the interface performance of the synthetic resin and the inorganic flame retardant is improved, the viscosity of the melt of the synthetic resin is reduced, the dispersion degree of the inorganic flame retardant and the like is improved to improve the processing performance, and the cable material obtains good surface quality and mechanical, thermal and electrical properties.

In summary, compared with the prior art, the invention has the following beneficial effects:

(1) by adopting the compounding of linear low-density polyethylene resin, high-density polyethylene and poly-1-butylene, the strength, toughness, heat resistance, cold resistance, tensile strength and creep property of the base material are improved, the environmental stress cracking resistance and impact resistance are improved, and the cracking resistance of the cable material is improved by adding the sheath forming fiber and combining the sheath forming fiber with the base material;

(2) by adopting the compound of the crystal II type ammonium polyphosphate, the magnesium hydroxide and the aluminum hydroxide as the inorganic flame retardant, the compound has the advantages of generating synergistic effect to play a good flame retardant effect, and because the crystal II type ammonium polyphosphate has high polymerization degree, good thermal stability, small hygroscopicity, low smoke, low toxicity and no molten drop, the precipitation rate in a cable material system is low, and the weather resistance and the electrical property are good; the flame retardant is compounded with magnesium hydroxide and aluminum hydroxide to serve as a flame retardant, so that the weather resistance of the cable material is improved while a better flame retardant is ensured, and the cracking resistance of the cable material is further improved;

(3) the physical performance of the cable material is improved by performing crosslinking pretreatment on the high-density polyethylene, the linear low-density polyethylene resin and the poly-1-butylene through a crosslinking agent to form a crosslinked structure, and then the inorganic flame retardant and the coupling agent are added in the second step, so that the interface performance of the synthetic resin and the inorganic flame retardant is improved, the viscosity of the melt of the synthetic resin is reduced, the dispersity of the inorganic flame retardant and the like is improved to improve the processing performance, and the cable material has good surface quality and mechanical, thermal and electrical properties.

Detailed Description

The present application will be described in detail with reference to examples.